Phenibut

Clinical contraindication: None listed; No clinical contraindication identified.
Best available evidence: Mechanism only
Half-life: Not recorded

Named in state rules?

CONot named

ORNot named

NMPending

Cite asPsilodex: phenibut · v2026.10.02

Clinical data and state rules are separate facts. Both are shown; neither is a decision.

01 Interaction with psilocybin

GABA analogue acting mainly at GABA-B receptors with gabapentinoid (alpha-2-delta) activity; sedative at higher doses. Regular use produces physical dependence, and withdrawal can be severe, including delirium and seizure risk.

Human data with psilocybin: None known: no published human data with psilocybin

Evidence types on this record

ThMechanism only (theoretical)

02 Pharmacology relevant to psilocybin

3 listed · counted on reports

Sedating or CNS depressant: Slows the central nervous system: drowsiness, slower reactions and impaired coordination, and slowed breathing at high doses. Effects add with other sedating substances. Sources [1][2]
Withdrawal or rebound if stopped abruptly: Stopping suddenly can cause withdrawal or a rebound of symptoms. Any change to the dose is the prescriber’s decision. Sources [1][2]
Lowers seizure threshold or carries seizure risk: Makes a seizure more likely, or has been linked to seizures. Sources [1]

03 State rules

Plain-language summary · official text governs

CO4 CCR 755-1

Not named

No provision names this medication or its class.

Colorado · checked 2026-09-30

OROAR 333-333

Not named

No provision names this medication or its class.

Oregon · checked 2026-09-30

NM7.35.3 NMAC (proposed)

Pending

New Mexico's clinical rules (proposed 7.35.3 NMAC) are not final. No provision naming this medication has been found.

New Mexico · checked 2026-09-30

04 Conditions to ask about

None linked

No condition named in state rules is linked to this medication.

05 Sources

Penzak SR, Bulloch M. Phenibut: review and pharmacologic approaches to treating withdrawal. J Clin Pharmacol 2024;64(6):652-671. — review of intoxication and withdrawal management; seizure risk in withdrawal
Jouney EA. Phenibut (beta-phenyl-gamma-aminobutyric acid): an easily obtainable 'dietary supplement' with propensities for physical dependence and addiction. Curr Psychiatry Rep 2019;21(4):23. — physical dependence and withdrawal
Martin R, Buffenstein I, Cho D, Kiyokawa M. Toxidrome of an easily obtainable nootropic: a case report of phenibut intoxication and withdrawal delirium. J Clin Psychopharmacol 2023;43(6):507-510. — GABA-B and alpha-2-delta mechanism; withdrawal delirium
US FDA consumer or public-health page (per-entry link) — not a lawful dietary ingredient

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